Means for controlling electric switches



Mar. 27, 1923 1,449,815 E. c. GoocH MEANS FOR CONTROLLING ELECTRIC SWITCHES Filed July 5, 1920 III 5 hm M MsALtorneg.

Patented Ma. 27, 1923.

UNITED STATES PATENT OFFICE.

ERNEST C. GOOCH,

OI ESTES PARK, COLORADO, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

MEANS FOR CONTROLLING ELECTRIC SWITCHES.

I Application filed July 3, 1920. Serial No. 393,832.

To all whom it may concern:-

Be it known that I, ERNEs r C. Goocn, a citizen of the United States, residing at Estes Park, county of Larimer, State of Colorado, have invented certain new and useful Improvements in Means for Controlling Electric Switches, of which the following is a specification.

It is customary to provide means whereby an electric translating device is connected to a source of supply by means of a plurality of switches which are provided for closing a, plurality of breaks in the connections from the source, and it is customary to close the switches simultaneously. It occasionally happens that by reason of a short circuit in the translating device, or from other causes such as a short circuit between the switch mechanism and the translating device, an excessive rush of current occurs when the switch mechanism is closed. In such a case the contact members of the switches are very apt to be welded shut by reason of the arcing caused at the switch contacts and the connections from the source of supply cannot be opened. My invention provides means whereby this dangerous condition is taken care of. I provide means whereby a portion of the switch mechanism cannot close until after the contacts of the remainder of the switch mechanismhave closed so that the connection to the source is never completed by the closing of the said remainder. In case thecircuit making contacts of the portion of the switches are welded shut due to the excessive rush of current, the remainder of the switch mechanism is free to open and thereby open the connection from the source of supply. In carrying my invention into efiect, in one form, I provide separately operated electromagnetic switches and current responsive means for opening the switch mechanism in response to the current taken from the source of supply. The arrangement is such that the operation of the current responsive means will ordinarily open the electromagnetic switch mechanism to disconnect the translating device from the source, but in case the contacts of part of welded shut, the current responsive means is nevertheless effective to open the remainder and thereby disconnect the translating device from the source. The remainder can not then be reclosed until the the electromagnetic switch mechanism are' portion opens, thereby preventing the contacts of the remainder being also welded shut.

For a better understanding of my invention, reference is had to the accompanying drawings wherein I have shown my inven tion embodied in systems of motor control, and in which Fig. 1 is a simplified diagram of a system of motor control; and Fig. 2 is a modification of the same.

Referring to Fig. 1, the translating devices to be controlled, in this case, the motor armatures 10 and 11, are adapted to be connected to a source of supply 12 by means of the electromagnetic switches or contactors 13 and 14. The winding circuits of these contactors are controlled by means of a pilot switch 15 and a push button or master switch 16. The overload relay 17 in circuit with the armature 10, the overload relay 18 in circuit with the armature 11, and the overload relay 19 in the connection to the two motor armatures in multiple, are provided for deenergizing the windings of the line contactors and causing these contactors to open in response to an overload on either or both motor armatures, or in response to any condition which causes a current to be taken from the source of supply which is in excess of that for which the overload relays are set to open. The line contactor 14 is provided with an auxiliary switch or interlock 20 which is provided for insuring that the contactor 13 will be closed before the line contactor 14.

The operation of my invention as thus constructed and arranged is as follows: In order to connect the motor armatures to the source of supply, the pilot switch 15 is first closed. The push button switch 16 is then depressed so as to make engagement with its lower set of contacts. The winding of the line contactor 13 is thereby energized from the source of supply, the connections being through the upper blade of the pilot switch 15, the winding of the contactor through the contacts of the overload relays 17, 18 and 19, the lower blade of the pilot switch 15 through the lower push button contacts, the interlock 20 of the line contactor 14 to the other supply conductor.- The line contactor 13 will thereupon close and in closin establish a maintaining circuit for itselt through its own switch contacts; in other words, in closing, the coniio , contactor through the push tactor 13 establishes a shunt circuit around the push button contacts and the interlock 20. When the push button is released so as to make engagement with itsupper set of contacts in accordance with its bias to that position, the winding of the contactor 14 1s energized to close this contactor and. connect the motor armatures to the source of supply. It will be observed that this line contactor cannot close until after the line contactor 13 is closed. The circuit for the winding of the contactor 14 is throu h the upper blade of the pilot switch 15, t e winding of the button 16, overload relays 17, 18 and 19, lower blade of pilot switch 15, through the contacts 01 the contactor 13, to the other supply conductor. When the contactor 14 closes, the interlock 20 is caused to make engagement with ts upper set of contacts. A maintalning circuit for thewinding 14 is established by reason of the shunt around the contacts of the push button established through the upper set of contacts for the interlock 20. 1n case of overload onveither one of the motor armatures or an overload on both of the armatures, either the overload relay 17 18 or 19 will, open, thereby deenerglzing the windings of both contactors and causing these cont actors to open the connections from the source of supply to the motor armatures. If there should be a short circuit in either one of the motor armatures or in the connections between the .line switches and the motor armatures, and the line contactors were simultaneously closed, the rush of current is very apt to weld the contacts together, so that the overload relays are not effective to open the remove this dangerous condition. My invention provides a means whereby this dangerous condition .is taken care of. It will be observed that the arrangement is such that the line contactor 13 must always close before the winding of the contactor 14 can be energized to close, so that if the contactor 14 is closed on a short circuit and its contacts welded shut, the overload relays are nevertheless effective to open the contactor 13 sinoe .no arcing would be caused at the contacts of 13 in closing and the contactor 13 is thus free to open. After the contactor 13 thus opens, the connections of the translating device to the source of supply cannot be reestablished until the contactor 14 is forcibly opened, since the windin of the contactor 13 is energized through the interlock 20, and the contactor 14 must be in its open position before this interlock can establish a circuit through its lower set of contacts. It will be seen, therefore, that I have provided means which not only insure that the connections to the sourceof supply will be surely opened when there is a short circuit or some other conditionwhich would conta'ctors and thereby cause an excessive rush of current from the source of supply, but the arrangement also provides means whereby the short circuit cannot be reestablished. The attention of the operator is thus called to the fact that a dangerous condition has been brought about, and he is prevented from reclosing the contactor l3 and thereby causing this contactor to be also welded shut.

The arrangement of Fig. 2 is slightly different from the arrangement of Fig. 1, and it is believed that it will be fully understood from a description of its operation. The interlock 20 on the contactor 14 is provided for merely closing one set of contacts, namely, the lower set. A resistor 21 is provided for insuring that the line contactor 14 will not close until after the line contactor 13 has closed. .The operation of this arrangement is as follows: With the members in their various positions as shown in the figure, the pilot switch 15 will firstbe closed. By reason of the fact that the circuit for the winding of the contactor 14 is completed through the contacts on the contactor 13, the contactor 14 will not close until after the contactor 13 has closed. The contactor 13 is energized to close when the push button 16 is depressed so as to make engagement with its lower set of contacts. A circuit is thereby completed through the upper blade of the. pilot switch 15, winding of contactor 13 through the contacts of overload relays 17, 18 and l9, lowerblade of pilot switch 15, lower push bdtton contacts through the interlock 20 to the other supply conductor. The contactor 13 in closing establishes a shunt circuit around the lower cont-acts of the push button switch and the interlock 20, so that this contactor will remain closed when the push button is released to make engagement with its up or set of contacts. It will be observed t at when the contactor 13 closes, a circuit is juo' made for the winding of the contactor 14 through the resistor 21-, but this resistor is of such a value that the current through the winding of contactor 14 is insuflicient to close the contactor. When the push button is released so as to make engagement with its upper set of contacts, the resistor 21 is short circuited and full value of current is thereby permitted to flow through the winding of contactor 14. .This contactor will then close and connect the'motor armatures to the source of supply. In this arrangement, in case there is a short circuit or other dangerous condition as described in connection with Fig. 1, the contacts of the contactor 14 will very likely be welded together, but the overload relays are nevertheless efi'ective to open the line contactor 13, and this contactor cannot be again energized to close, since after it opens its contacts, the circuit for this winding must be completed through the interlock 20, and this interlock cannot close its contacts until the contactor 14 opens. a

In order to disconnect the motor armatures from the source of supply, the normally closed stop push button switch 22 will be depressed, thereby deenergizing the contactor windings.

In the arrangement of Fig. 2, if the re sistor 21 is of a sufiiciently high value, the line contactors can be opened by depressing the push button 16 and then releasing the same before the contactors can reclose'? In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown-is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. Means for controlling the connection of an electric translating device to a source of supply comprising a plurality of switches for completing the connection by closing a plurality of brakes in the connection from the source and interlocking connection between the said switches for preventing the closing of a portion of the breaks in the circuit by thesaid switches until after the remainder of the breaks is closed, and'for then preventing the reclosing of the said remainder unless the said portion is opened, whereby ti a circuit is never completed by th closing of the said remainder so that the said remainder is free.

to open but cannot be reclosed until the said portion is opened.

2. Means for controlling the connection of an electric translating device we source of supply comprising two electromagnetic line switches for closing two breaks in the connections to the source .of supply, a master switch for controlling the said line switches, and connections under the control of the said master switch for insuring that the line switches are successively closed and for preventing the first of said line switches from reclosing after the opening thereof until the last line switch to close has been opened, whereby the circuit is never completed by until the last line switch of a plurality! the closing of the first line switch and this switch may open but cannot be reclosed to close is opened.

3. Means for controlling .the connection of an electric translating device to a source of supply comprising two electromagnetic line switches for closing two breaks in the connections from the source to the translating device, master switch mechanism for controlling the electromagnetic switches, current responsive means for opening the electromagnetic switches, and connections under the control of the said master switch and one of the said line switches for preventing one electromagnetic switch from closing until after the other is closed, and for preventing the first "electromagnetic switch from reclosing after the opening thereof by the operation of the said current responsive means until the second line switch to close is opened! 4. The combination in a circuit controller of electroresponsive line switches, means for automaticall deenergizing the said switches upon t e rence of abnormal electrical conditions in the controlled circuit, a controller for the said line switches, and circuit connections for said switches necessitating energization of one prior to energization of another in order to close the controlled circuit and then necessitatin the opening of both of said switches beibre the said controller is rendered effective to again control the said switches to close the controlled circuit.

5. The combination in a circuit controller of two electroresponsive line switches, means for automatically deenergizing the said switches upon the occurrence of abnormal electrical conditions in the controlled circuit, a controller for the said line switches, circuit connections for the said switches necessitating the energization of the first prior to the energization of the second in order to close the controlled circuit, and auxiliary switch mechanism associated with the said second line switch for preventing the reclosing of the said first line switch after the opening thereof until the said second line switch is open.

'In witness whereof, I have hereunto set my hand this 28th day of June, 1920.

ERNEST C. GOOCH.

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